By: Kelly M. Hersh, FNP-BC
So you or a family member was just diagnosed with a peanut or tree nut allergy. You understand the importance of strict avoidance, including careful label reading, and a treatment plan for what to do in case of an accidental ingestion, but now what? Days or weeks after leaving the allergist’s office, questions often pop up. Let’s review some common questions we get asked:
Question: My child was diagnosed with peanut allergy. Does that mean s/he should avoid tree nuts too?
Answer: Not necessarily. Peanuts are legumes, which means they are not botanically related to tree nuts (almonds, cashews, walnuts, etc). Many people allergic to peanuts can tolerate tree nuts and vice versa.1 That said, someone having any food allergy is at a higher risk for having other food allergies, so if your child is not already currently eating tree nuts, it is a good idea to check with your allergist to see if they should be tested prior to introduction.
Question: I am peanut allergic, but I have heard eating foods fried in peanut oil might be ok. Is this true?
Answer: Most peanut allergic patients can tolerate highly refined peanut oil. This is because the peanut protein is removed during processing. Gourmet peanut oils that are cold pressed, extruded, or expelled can contain enough peanut protein to cause a reaction, so they should be avoided.2 These oils do not have as high of a smoke-point as refined peanut oil and are not meant to be used in high-heat cooking such as frying. If you are unsure which type of oil is in a food, its safest to avoid it.
Question: Are water chestnuts, nutmeg or shea nuts tree nuts?
Answer: No. These are generally well tolerated amongst tree nut allergic patients.1
Question: What about coconut?
Answer: The FDA classifies coconut as a tree nut, but it is actually a seed of a drupaceous fruit. True coconut allergy is rare.1, 3 If you have been avoiding coconut due to a history of allergy to other tree nuts, speak with your allergist to see if you might be a candidate to test and see if coconut can be added to your diet.
Question: Can I be allergic to some tree nuts but not others?
Answer: Yes. While at least half of patients with a tree nut allergy are allergic to more than one tree nut, it doesn’t necessarily mean they are allergic to all of them. There are certain tree nuts such as cashews and pistachios, that have protein structures that are very similar to each other. This can causes the immune system to react if either nut is eaten since it can’t differentiate the two. This is called cross-reactivity. Not all tree nuts are as closely related and individuals allergic to one kind may be able to eat another kind. Each person’s situation is different. Our providers are able to review your history and testing results to determine whether it is most appropriate to avoid all tree nuts or if you may be able to introduce selected tree nuts into your diet.
Question: Is there a chance I could react if someone else near me (like in an airplane!) is eating peanuts?
Answer: Fortunately this is unlikely. Peanut allergy is due to an allergy to specific proteins found in peanuts. These proteins are not found in the compounds that create the odor of peanuts. Additionally, there is no evidence that peanut protein is aerosolized enough to cause a reaction in allergic individuals just by being around people snacking on them.4 This is not to say throw caution to the wind. For air travel or even going out to eat, I do tell my patients to wipe down tables, trays and seats before sitting down to remove any potential peanut or tree nut residual that may have been left by a previous occupant. Accidental transfer of peanut residual to the mouth after touching a contaminated surface could indeed cause a reaction.
I hope this Q & A helped answer some lingering questions. If you have any further questions or concerns, please give our offices a call. Our staff can determine whether a question can be answered over the phone or if making an appointment is best so more in depth concerns can be addressed by one of our providers.